The present invention relates to a process and a device for manufacturing at least one metal strip of small width, as well as to a metal strip manufactured by this process.
The subject of the invention is also a nozzle used for the manufacture of this metal strip.
By strip is meant a body of elongate shape, the transverse dimensions of which are very much less than its length. Wires, sheets and metal tapes are, for example, considered as metal strips.
For some technological applications, industrial concerns are obliged to employ metal strips of particular dimensions, and especially require that these strips have a minimum thickness in order to guarantee, for example, their hot oxidation resistance when they are in contact with a highly oxidizing medium as, for example, for metal supports for catalysts.
Among the techniques used hitherto for enabling metal strips to be produced, that which consists in ejecting a molten metal or metal alloy through orifices of circular shape which are made at the lower part of a nozzle with a view to depositing it onto a moving tooling member located beneath the said nozzle, so as to bring about the solidification of this metal or this alloy on the said cooling surface, is especially known.
Such orifices are uniformly arranged at the lower end of the nozzle along a direction transverse with respect to the direction of movement of the surface of the cooling member and face downwards opposite the said cooling surface.
The cooling member is formed, for example, by a wheel.
This technique makes it possible to form, on the cooling surface, metal strips whose small width lies between 0.5 and 1.5 mm and whose thickness is limited to certain values which depend on the widths of these strips.
Thus, an orifice whose diameter is equal to 1 mm makes it possible, for example, to form, on the cooling surface, a metal strip whose width is equal to 1 mm and whose thickness may not exceed 30 .mu.m, which is unacceptable for applications where a minimum thickness of 40 .mu.m is required.
In order to overcome this problem, several, approaches have been envisaged by the Applicant's Company.
First of all, the Applicant's Company has envisaged, in a logical manner, increasing the diameter of the circular orifices of the nozzles so that the thickness of the metal strips is greater.
However, the consequence of this approach was to increase the width of the said strips more than their thickness and the metal products thus obtained were no longer in conformity with the dimensional requirements of the users.
Next, the Applicant's Company envisaged reducing the speed of movement of the cooling member in order to increase the thickness of the metal strip formed.
Now, by decreasing the speed, a loss of adhesion was observed of the metal on the cooling surface, which can lead to a deterioration of the solidification of the metal constituting the metal strip.
For this purpose, tests were carried out by modifying the nature and the roughness of the cooling surface so as to enhance the adhesion of the metal on the said cooling surface.
However, such modifications did not contribute to the enhancement of the adhesion on the surface of the cooling member.